The present invention is directed to a rotor hub fairing system, and more particularly, to a rotor hub fairing system which reduces overall drag for a high-speed rotary-wing aircraft having a counter-rotating, coaxial rotor system.
Typically, the aerodynamic drag associated with a rotor system of a rotary wing aircraft is a significant portion of the overall aircraft drag, typically 25% to 30% for conventional single-rotor helicopters. The rotor system drag increases for a rotary wing aircraft having a counter-rotating, coaxial rotor system primarily due to the additional rotor hub and the interconnecting main rotor shaft assembly between the upper and lower rotor systems. For high-speed rotary wing aircraft, the increased drag resulting from the counter-rotating, coaxial rotor system may result in a relatively significant power penalty.
The aerodynamic drag of the dual counter-rotating, coaxial rotor system is generated by three main components—the upper hub, the lower hub, and the interconnecting main rotor shaft assembly. The drag contribution may be approximately 40% for each of the rotor hubs, and 20% for the interconnecting shaft assembly.
Accordingly, it is desirable to provide a drag-reducing rotor hub fairing system for a rotary wing aircraft having a counter-rotating, coaxial rotor system.